Question

Suppose you place an object 8 cm in front of a converging lens and the image appears 16 cm on the other side of the lens. What is the focal length of the lens?

Answer 1

Answer:

5.33 cm

Explanation:

The lens equation states that:

$\frac{1}{f}=\frac{1}{p}+\frac{1}{q}$

where

f is the focal length

p is the distance of the object from the lens

q is the distance of the image from the lens

In this problem,

p = 8 cm

q = 16 cm ( the sign is positive since the image is real, which means it is formed on the other side of the lens)

Substituting into the equation,

$\frac{1}{f}=\frac{1}{8 cm}+\frac{1}{16 cm}=\frac{3}{16 cm}$

$f=\frac{16}{3}cm=5.33 cm$